Rectifier



J1me J. WANTZ ET-AL 1,761,246

RECTIFIER I Filed May 10, 1924 2 Sheets-Sheet 1 mvamoas xawamz & 11 2mm.

M RTTORNEX June 3, 1930. "J. B. wAl rrz ET AL RECTIFIER 2 Sheets-Shset 2Filed May 10 N EN'TOR5 3.5. wmnz & ma. mama BY RTTORNEY Patented June 3,1930 UNETE FFIQE STATES iPATEZiiT (BAX PARK, ILLINOIS, ASSIGNORS TOILLENGIS, A CORPORATION OF NEW RECTIFIER Application filed May 10,

The subject matter of the invention heroinafter disclosed relates toadvances in the art of rec ing pcriodicall 'arying electric currents,the invention including among its objects the sin plying, for rectifying'iigh potential, of a corona-free or coronaless mechanism withoutcoronawoof parts, and the provision of an appliance adapted to convertthe entire wave or any desired portion thereof, of a periodicallyvarying current into unidirectional flow.

Use of X-rays for purposes other than photography has determined anecessity for currents of very high voltaoes to excite the tube, and therequirement or employn'ient of more than the tops of current waves. Highvoltage rectification in conventional appara tus has been impracticablebecause of the formation of corona and excessive arcing. The apparatusheretofore designed for use in conjunction with X-ray apparatus hasselected the tops of waves only or a small. portion thereof and noadequate provision for rectifying; the whole of each periodicallyvarying wave, or a substantial portion thereof, has heretofore beenmade. The amiaratus, the subject matter of this pplication for patent,is for the purpose of olin'iinating corona and preventing excessivearcing, and includes measures for enlarging the proportionate amount ofeach wave rectified.

The objects of the invention therefore, in clude the adaptation of meansfor dctorn'iining in advance the proportion or volume of a current waveto be rectified; the selection of improved forms whereby arcing isreduced and corona avoided; and the production of a mechanism theproportions of which permit of compactness when high voltages areemployed.

These, and such other objects as may hereinafter appear, are attained bythe construction, arrangement, and combination of the several parts ofthe device to be hereinafter described and fully illustrated in theacixnnpanying' drawings, hereby made a part of this specification, andin which Figure 1 is a schematic diao'rain of the invention as employedwith an X-ray tube;

1924. Serial N0. $12,488.

Figure 2 is an end view of a mechanism em bodying the invention;

Figure 3 is a top view of suchn'ieclianism;

Figures 4;, 5 and 6 are, respectively, a front elevation, a back view,and a vertical section of one electrode; and

Figures 7 and 8 are, respectively, side and top views of the revolvingswitch;

Figures 9 and. 10 are diagrammatic rcpresentations of the polarity ofthe electrodes and the electrostatic fields formed in the switch.

Like reference characters are used to designate similar parts in thedisclosure which follows and in the several views in the drawings.

it is well known that for successful employment of Roentgen ray tubesunidirectional currents of high potential are required. Various planshave been devolved for generating and supplying such unidirectionalcurrents,

and it is now the more popular practice to employ an alternating currentsource and a rectifier for supplying current to such apparatus. it nustbe ui'idcrstood, however, that the invention here disclosed inconjunctionwith an alternating current supply may be adapted for usewith equal cii'ectiveness upon an arrangement cn'iploying a directcurrent source.

Reference should be had to Figure 1. Ordinals 11 and 12 designate mainsconnected to any suitable source of alternating current of moderatevoltage and having any one of the commercial periodicities. A step-uptransformer is in circuit with said mains, the primary of saidtransformer being indicated 1S and the secondary 14-, the latter beingemployed to excite an i'i ray tube 15. Intermediate secondary 14. andtube 1-5, the rectifying switch harming the subject matter of thisapplication is disposed.

A further examination of Figure 1 dis closes that the tube 15 here shownof the hot cathode type, and that a second transformer having a primary16 connectine mains 11 and 12 and a secondary 17 adapted to heat the catiodc of tube 15 is employed. The Wiring scheme set forth isconventional, and may be altered without deviating from the spirit ofthe invention.

High tension alternating cur 'ent is conveyed from sec ndary ll throughtcrn'iinals 1i and 14 by mains 1S and to a. pluri lity of equally spacedelectrodes, identical in construction and here shown arr end inelectrically connected vertical the right hand pair being d ignated 20and 21, and the left hand pair, 2- and 23. Directly opposite each ofsaid. electrodes, 20, 21, 22 and 225 and spaced apart therefrom aresimilar electrodes, but arranged in electrically connected horizontalpairs, the upper pair 1 eing designate l by the numerals 2i and and thelower by the numerals 26 and 27.

Eli

The electrodes 20, 21, and 23 are cha :d with 36]10tllCilll'y' varyingelcctro-nnnive force of high potential, from secondary 1 1 and in orderto properly excite tube 15 which is in circuit with electrodes 25, 26and a revolving switch is employed, such switch comprising a. shaft 30driven by a synchronous niotor 31, also in circuit with mains 11 and 12.

Radial insulating arnis preferably oppositely disposed and two innumber, project from shaft 30, to be joined at their free onus by across member or plurality of cross inen1 bers 33, of electricallyconducting material and having ball ends 3%, also of conductingmaterial, said cross members when used in series as illustrated inFigure 1. being; insulated one from another by se arators 3i allixed toarms 32.

The operation of the switch is manifest from an inspection of Figure 1.The shaft 30 is rotated. synchrmiously with the gencu a lion insecondary 1 1 of periodically Varying: impulses of high potential. Uponone inipulsc, the path of current is from one terini nal 14-. of thesecondary ft to electrode 2), through cross member 33 to cl i-"rode 24',to tube 15, the circuit being; completed from tul 15 to the other to'niinal 1 1" of the secondary 1 1 through electrodes 37 and 23 connectedby the cross ineinber at the opposite end o the rotatin switch. ign,

With the change in the the rotating switch advances 9O mechanicaldegrees and the circuit is then from the last mentioned terminal (1 1)of the secondary 1&1: to electrode 22, thence through in -n'ibcr 323 toelectrode 25 and to tube 15, the circuit being completed by electricalconnect ion through electrodes 26, the opposite cross inc nber 32;}. andelectrode 21 to the iirst mentioned terminal 14 of seconcary 1 1-.

As the again changes, the rotor udvances another quarter turn and thecircuit is again as first dc 'ibcd. On the succceling change of thesign, the switch a d ranccs a quarter turn and the second describedcircuit is reestablished. A unidircctioiuil flow of current for excitingtube 15 is thus established.

Keeping in mind the schematic d Figure 1, reference should now be h .dto 1 lg;

ures 2 and 3, end and top Views of one embodiment of the inreutiou. Asuitable box or liilatforni base It is provided, such base to be of woodor similar niate'ial sturdily constructed and suitably braced. lVithinthe base A is a traiisiornicr l) comprising prinzary 13 and secondaryl-il.

11 frame C conipr s". zontally dispose t ode and thence through theadjacent upright C of frarne C to electrode 22.

On the direct current (unidirectional) side of the rectifier, electrodes2-1 and 25 are electrically connected and are in circuit with a main(not shown) leading to and from one terminal of an X-ray tube. while theelectrodes 26 and 27, nituated beneath electrodes 24: and of Fig 1e 3and opposite electrodes 21 and 23 of Figure 2 but not shown, areelectrically connected and are joined to a second main (not shown)supplying high potential current to the other tern'iinal of said X-raytube. Electrodes 2411 to 27 are mounted upon uprights C and C, 241: and25, and 26 and 27 being: joined by horizontally (lisposed mains whichare shown in li igurcs 2 and 3.

It will be noted that each of the electrodes 20 to 27 inclusive, (seeFigures 1, 5, and 6) comprises a plane surface or disc 40 and a flangeor riin 41 of a spheroidal configuration. Each electrode has a turned inedge 12, and is of a diameter in excess of that of the sphere of visiblecorona which would be formed about a point just before sparloover at thevoltage for which the electrode is designed. The electrical connectionin said electrodes is obtained through stem or stud 13, prefe ablyprojecting bachwardly from the center of the contacting face of disc 410of each electrode. Such electrodes, when of the dian'icter suggested orof greater diameter and be :ause of their plane faces 10 and spheroidalrims 41, are coronaproofthat is, of effective configuration and diameterwhereby to PIQYPDl corona before spark-over. As the inturued edges 12 ofelectrodes 20 to 27 inclusive fall within the electrosi a tic fielcformed by the said electrodes, no leakage or corona appears upon theireon'iparatively sharp edge...

nynchronous motor 31 is disposed upon a smaller platform r. supporting:the transformer D h aving; its secondary 17 in circuit with the cathodeof tube 15, and rotates shaft 30 which is journalled at its outer end ina bearing provided therefor upon an extension cross bar C betweenupright C and C Radial arms 32 of insulating material, preferably extendthrough shaft 30 and are tapered to reduce air resistance. Across theirextremities (see Figures 1, 7 and 8) is a rectangular frame comprisingcross bars 33 having ball ends 34, and separators 35, the cross member33 being of insufficient diameter and radii to prevent corona at thecapacity for which the machine is designed and the ball ends 34, whichmay be solid, are also of insuflicient diameter and radii to preventcorona before spark-over. Separators 35 are of insulating material andare circumferentially grooved for the purpose of increasing theirleakage surfaces.

The course of the high potential current through the rectifier has beenpreviously made clear in the description based upon Figure l. Theapparatus described is adapted for use in all types of X-ray workbutmore particularly to such as necessitate the use of a large amount ofeach wave of current. By the spacing of connectors 33, that is, bylengthening or shortening separators 35, more or less of each currentwave is rectified, and the whole of the wave, or substantially the wholethereof, may be passed to the tube 15. As indicated a single crossmember 33 may be employed, and the shape thereof may be varied. Again, asingle radial arm 32 may be used, and other modifications may be hadwithout departing from the invention, the provision of a coronalessrectifying switch comprising parts that are not corona proof. Thevarious line switches and other incidental apparatus found in commercialX-ray outfits have been omitted for any one skilled in the art willinstantly add, in applying the invention to a commercial purpose, suchadditional apparatus as is desirable for the specific problem in hand.It is also manifest that the device has equal application in a directcurrent apparatus for supplying high potential to an X-ray tube.

Reference should again be had to Figures 1, 2 ant '3. The severalelectrostatic fields formed in the switch consist of electrostatic linesof force emanating at right angles to the surfaces of the electrodes, 20to 27, the greatest intensity being between electrodes of oppositepolarity.

Electrodes 22 and 23 are always of opposite polarity from electrodes 20and 21.

Whenever the connectors 33 are intermediate two of the electrodes 20 to23 inclusive, and two of the electrodes, 24: to 27 inclusive,

electrodes 24 and 25, and 26 and 27 become oppositely polarized, thepolarity of said electrodes being unchanging. With the movement of rotor32, as will be seen from Figures 9 and 10, two electrostatic fields areformed between oppositely faced electrodes,

for in the position shown in Figure 9, one field exists betweenelectrodes 21 and 26, and another between electrodes 22 and 25. As theother pairs of opposed electrodes, 20 and 24-, and 23 and 27 betweenwhich the connectors 33 serve to pass current are of like polarity, noelectrostatic field exists therebetween. In Figure 10, fields existbetween electrodes 20 and 24, and electrodes 23 and 27, but no fieldsexist between the remaining electrodes, 21 and 26, and 22 and 25, forthese pairs of opposed electrodes are of the same polarity and areconnected by members 33.

It may therefore be stated that there are six electrostatic fieldsexistent in the switch whenever the rotor 32 is in such a position thatelectrical connection is established between any two of the alternatingcurrent elec trodes and the opposing two unidirectional currentelectrodes. As each of the two possible connections are establishedbetween the alternating and pulsating direct current sides of theswitch, through the four connecting positions of rotor 32, there are twohorizontal fields on the alternating current sideof the switch, twovertical fields on the direct current side, and two transverse fieldswhich may be said to be rotating.

As the rotor 32 at each advance of a quarter turn and at its oppositeends connects similar- 1y charged electrodes, the connectors 32 whenconducting current always lie Within a shield ing influence of connectedelectrodes of ejlfective radii to prevent corona before sparkover. Thatis, there is no preliminary corona.

It is, of course, to be understood that the whole switch compriseselectrostatic fields, but that the lines of force described in detailhere are the most intense lines of force in the switch. Corona prior tospark-over is wholly avoided by the disposition of the connectors, whencarrying high potential, between two corona-proof electrodes, hence itis not material that the connectors themselves should be corona-proof.

Thus, the most intense lines of force of the electrostatic fields of theswitch on the alternating side of the'switch are never parallel to themost intense lines of force on the direct current side, but alwaysperpendicular thereto, while the lines of force of the transverse fieldsintermediate the alternating and direct current sides of the switch areat an angle of 90 degrees to each of the first mentioned lines. Animaginary line coincident with the lines of force of greatest intensityin the several electrostatic fields would follow three directions, eachat an angle of 90 degrees to the other.

Asthe electrodes 20 to 23, on one side of the switch, and 24 to 27, onthe other side of the switch, are effectively insulated one from anotherby the air space therebetween, and are of effective radii and diameterto prevent corona, the machine here described is wholly free from coronaand its ill effects upon patient, operator and surrounding objectsresulting from the generation of nitrous oxide and ozone.

The invention may therefore be said to comprise a symmetricalarrangen'ient of the electrodes producing symn'ietrically disposedelectrostatic fields, the insulating}; air space intermediate theoppositely charged electrodes being constant at all times. It is, ofcourse, to be noted that the insulating arangement herein employed issymmetrical with respect to the stationary electrodes, and that therotor is of such configuration and form that the disturbance incident tothe movement of said connecting member between the several electrodeshas a minimum disturbing influence upon the insulating arrangementthereof.

Claims:

1. A rotary rectifying switch for high ten sion current comprising thecombination of relatively movable electrodes, one of said electrodeshaving a relatively large conducting surface and an inturnedper-ipl'iery whereby corona discharge is reduced, and the othercomprising a bar of relatively slight diameter.

2. A rotary rectifying switch for high tension current comprising thecombination of relatively movable electrodes, one of said electrodeshaving a relatively large conducting surface comprising a disk likeportion and an inturned periphery whereby corona discharge is reduced,and the other comprising a bar of relatively slight diameter.

3. A rotary rectifying switch for high tension current comprising thecombination of relatively movable electrodes, one of said electrodeshaving a relatively large condncting surface comprising a plane boundedby a spheroid whereby corona discharge is reduced, and the othercomprising a bar of relatively slight diameter.

4. A rectifying switch for high tension current comprising thecombination of an electrode having a large relatively flat conductingsurface and turned in edges whereby corona discharge is reduced, with arotating conducting member of relatively slight conducting surface.

5. A rectifying switch for high tension cur rent comprising thecombination of an electrode having a large relatively flat conductinsurface comprising a plane and turned in edges whereby corona dischargeis reduced, with a rotating rod connector of relatively slightconducting surface.

6. A rotary rectifying switch for high ten sion current comprising thecon'ibination of relatively movable electrodes, one of said electrodescomprising a stationary plane, and having arelatively large conductingsurface and an inturned periphery whereby corona discharge is reduced,and the other comprising a movable bar member of relatively smallconducting area.

7. In a rectifying switch for high tension current, alternating currentand uni-directional current electrodes comprising stationary spheroidsat the opposite sides of said switch, whereby corona discharge isreduced, and a movable conducting electrode of relatively slightconducting surface intermediate said spheroids.

8. In a rectifying switch for high tension current, alternating currentand unidirectional current electrodes comprising spaced spheroidalmembers whereby corona dis charge is reduced, and a movable ballconductor member of a relatively small fraction of the diameter of saidspheroidal member and intermediate said spheroidal members.

9. A rectifying switch comprising a plurality of stationary electrodesof relatively large conducting surfaces, and an electrode movable withrespect thereto, said mo able electrode comprising a plurality ofconducting members the amount of separation of which deterl'nines theproportion of each al ternate current wave to be rectified.

10. A rotary rectifying switch comprising spheroidal electrodes l'iavingrelatively large conducting surfaces, and a movable electrode comprisingconducting members of relatively small conducting surfaces and arrangedin series, the amount of separation between said conducting members inseries determining the proportion of eacn alternating current wave to berectified.

11. A rectifying switch comprising stationary electrodes, and spacedopposed movable elcctrodes, each of the latter comprising a plurality ofspaced apart conducting members insulated one from another, the amountof separation between said conducting members detern'iining theproportion of each alternating current wave to be'rectiiied.

12. In a rectifying switch, a source of alternating current, a pluralityof stationary electrodes having relatively large flat plane conductingsurfaces arrangcd oppositely to one ano ier, and a rotor having a motorfor driving it synchronously with said alternating curri-mt and carryinga conducting electrode of relatively slight coru'lucting surfaces havinga path of movement intermediate the conducting faces of said stationaryelectrodes.

13. In a rectifying switch, a plurality of stationary electrodes havingoppositely arranged relatively large conducting surfaces, and aconducting electrode movable intermediate said stationary electrodes andhaving spherical ends connected by a cross member, s 'd spheri cal endsand said cross member heiug of a relatively slight diameter, suchdiameter being a small fractional part of the diameter of a stationaryelectrode.

1%. In a rectifying switch, pairs of electrodes of spheroidalconfiguration having a large conducting surface and spaced apart adistance a fraction of their diameter, and a conducting electrodecomprising a cross bar of relatively slight diameter and intermediatesaid pairs of electrodes, said bar electrode and spheroidal electrodesbeing relatively movable.

15. In a rectifying switch, a conducting elect-rode comprising sphericalterminals of relatively slight conducting surface, a cross barintermediate said terminals and of relatively slight diameter, saidelectrode being movable relatively to stationary electrodes, andstationary electrodes comprising a plurality of paired spheroids ofrelatively large conducting surfaces and spaced apart a fraction of thediameter of said spheroids.

16. In a rectifying switch having alternating current and unidirectionalcurrent sides, a plurality of spaced disk-like electrodes, there beingfour of said disks at one side of said switch with parallel faces, andfour at the other side of said switch similarly arranged, so that themost intense lines of electrostatic force in the opposite sides of saidswitch are at angles of ninety degrees to the most intense lines ofelectrostatic force across said switch and a movable connector forestablishing electrical connection between oppositelyrdisposedelectrodes.

17. A rectifying switch having an unidirectional current side and analternating current side, a plurality of oppositely disposed and equallyspaced disk-like electrodes arranged four on each side of the switch sothat the most intense lines of force on opposite sides of said switchare perpendicular to one another.

18. A rectifying switch having stationary electrodes, and a movableelectrode comprisin g a plurality of separated conducting membersinsulated one from another, the amount of separation between saidconducting members determining the proportion of each alternatingcurrent wave to be rectified.

19. A rectifying switch comprising opposed electrodes, and a movableintermediate electrode, said latter electrode comprising a plurality ofspaced apart members insulated one from another and being spaced torectify a predetermined or selected part or porportion of an alternatingcurrent wave.

JULIUS B. WVANTZ. ARTHUR A. GROTHE.

